Understanding sourdough functionality in wheat breadmaking

Promovendus/a: Celine Verdonck

Promotor(en): Prof. dr. ir. Christophe Courtin

Sourdough bread is popular and many people see it as a healthier and tastier choice than yeast-leavened bread. Interest in the possibilities of using sourdough has grown, both in the industry and in research. Sourdough could be a clean-label ingredient contributing to an airy texture in wholemeal bread. Achieving such texture clean-label is currently one of the major challenges for bakers. This would encourage more people to eat wholemeal bread, which is beneficial as it has a better nutritional value than white bread but is still not widely chosen due to its less popular texture.

There are enthusiastic stories about the benefits of sourdough in bread. However, with so many recipes for making sourdough and sourdough bread, there is little consistent scientific evidence on how sourdough impacts the breadmaking process and bread quality. Our research shows that with the addition of sourdough, the required water and mixing time to achieve an airy wholemeal bread, are reduced. This is partly due to the organic acids formed during sourdough fermentation. These organic acids increase interactions between dough constituents, especially gluten proteins. This makes the dough stronger and allows it to retain the gas produced during fermentation better, resulting in wholemeal bread with a better, airy crumb structure.

But beware! It became clear that making a good dough with sourdough or organic acids is tricky. Small variations in water quantity or mixing time can have big effects. Everything needs to be just right to bake the perfect loaf. One mistake, and you’ll end up with a brick instead of a beautiful loaf!

Additionally, sourdough can also affect the nutritional value of wholemeal bread. The resting time of the bread dough and the microorganisms in the sourdough play a crucial role here. The longer the dough rests, the more organic acids and soluble fibres it contains, and the fewer mineral-complexing components remain in the bread. These properties could positively affect blood sugar levels, feelings of fullness, and mineral absorption when eating wholemeal sourdough bread.

Based on these results, it makes sense to distinguish sourdough breads by their fermentation and proofing time, while considering the microbial consortium. For example, short-fermented sourdough-type bread could be called “bread with sourdough” and long-fermented sourdough-type bread could be referred to as “sourdough bread”. This would help researchers communicate more accurately with the industry and consumers about how sourdough affects bread quality and finally, may help in formulating health claims for different types of bread.